1. Field of the Invention
This invention relates generally to heterocyclic macromolecules. It relates particularly to polybenzoxazoles by the nucleophilic displacement reaction of di(hydroxyphenyl) benzoxazole monomers with activated aromatic dihalides.
2. Description of the Related Art
Polybenzoxazoles (PBO) are heterocyclic macromolecules which were first synthesized in a two-step process by the initial formation of soluble poly(o-hydroxy)amide)s through solution condensation of aromatic diacid chlorides with bis(o-aminophenol)s followed by thermal cyclodehydration [T. Kubota and R. Nakanishi, J. Polym. Sci., Part B, 2, 655 (1964)]. Since then several methods have been utilized in their synthesis. The most common synthetic method for PBO involves a polycondensation of bis(o-aminophenol)s with aromatic diacid diphenyl esters [W. M. Moyer, Jr., C. Cole, and T. Anyos, J. Polym. Sci., Part A, 3, 2107 (1965)]. Another preparative route involves the solution polycondensation of the hydrochloride salts of bis(o-amino phenol)s with aromatic diacids in polyphosphoric acid [Y. Imai, I. Taoka, K. Uno, and Y. Iwakura, Makromol Chem., 83, 167 (1965)]. Another synthetic method involves the initial formation of poly(o-hydroxy amide)s from silylated bis(o-aminophenol)s with aromatic diacid chlorides followed by thermal cyclodehydration to PBO [Y. Maruyama, Y. Oishi, M. Kakimoto, and Y. Imai, Macromolecules, 21 (8), 2221 (1988)]. A recent preparative route involves the reaction of aromatic bisphenols with bis(fluorophenyl) benzoxazoles by the nucleophilic displacement reaction to form PBO [J. G. Hilborn, J. W. Labadie, and J. L. Hedrick, Macromolecules, 23, 2854 (1990)].
Primary objects of the present invention are to provide new polybenzoxazoles (PBO), a new process for preparing PBO, and new monomers used for the preparation of PBO. Another object is to provide new PBO that are useful as adhesives, coatings, films, membranes, moldings, and composite matrices.